You're going to have to pick one here. I'm not the Chemist/Salve-maker advocate; I'm the one who said I'd rather see potion-use subsumed into an integral part of another job (ideally one that would form organically from existing plot points) than try to run such a scant concept as a job's basis and flesh it out arbitrarily from there. So a salve-maker wouldn't use blood infusions? Fair enough. I never said they (the vanilla class concept) should. My point was that there are chemist-derivatives (auger/empirist/plague doctor/etc.) that could make potion-use the center of their kit but could spice that up into some compelling cohesion sufficient to make a truly fleshed out job -- that is to say, with the addition of other means and styles of item usage that could run in a similarly ominous/pragmatic/tactical style.
You already know my stance on WHM abandoning its elements, so let's skip to SCH and hexes and the implication that anything and everything to do with plague would have to be the sole purview of SCH (despite their in-game lore including only one study into an ancient plague).
No doubt, Hexes fits their tactical style to some extent, in that the have situationally-best graphical and material complexities that brings about some desired result, but it seems almost the opposite of their aesthetic. Hexes are usually a symbol of the occult. Bone sigils? Dreamcatchers? Warding talismans? These smack of a sort of anti-academia.
Heck, just take the sample name, empirist (another name for a "quack" doctor outside the scholarly order, back in the era of leeching and treatment of the four humors), one who believes only what they see and have experimented for, placing little to no value in history, historical solutions or the workings of the world outside their region of work -- it's the antonym of a scholar.
In the scenario I proposed, the Black Rose-affected area would be incredibly distinct zone, which may largely follow altogether different rules of magic as aether is leeched from people and plants such that latent aether becomes simultaneously stifling and unusable (to most, at least). That's why I was drawn to the irony here. You'd have a new order of 'uneducated' or 'folk-remedy' doctors whose cures have actual, proven efficacy in the surrounding confusion, be that hexes (abjuration), learning how to avoid the semi-sentient miasma of the ever-thickening latent aether (augury), counter-infections, synthesis, adaptation, or whatever else. These seemingly occult and unproven items could actually be among the few things to work in that novel and chaotic zone. Thus, you'd have a potions-centric class that is an organic fit for the continuing plotlines, complete with a focal zone that'd be plenty fun in its own right. I'd sooner take that over trying to pass off "throws potions" as a complete and compelling concept or pushing anything and everything plague related to the 'scholardom' (despite their historical reluctance to have anything to do with major plague outbreaks).